Diesel fuel



Patented Jan. 8, 1946 DIESEL FUEL Edwin M. Nygaard, John H. McCracken, and

Nathan H. Hamilton, Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application October 20, 1943,

' Serial No. 507,026

13 Claims.

This invention has to do with fuels for internal combustion engines'of the Diesel or compression ignition type and, more particularly, has to do with the improvement of such fuels by the addi-' tion' thereto of a characterizing ingredient.

In order that a Diesel engine may be operated at maximum efficiency ignition of the fuel should be essentially instantaneous. Delayed ignition or poor coordination between the compression and cylinder conditions is the cause of knocking in Diesel operation. As is well known to those familiar with the art, this condition may be remedied byadding small amounts of certain materials or compounds to Diesel or compression ignition fuels. Compounds possessed of such characterizing ability accelerate the ignition of the fuel and thus provide a means whereby the ignition delay period of the fuel is rendered extremely short. In this way, the better grades of Diesel fuels are enhanced and low-grade hydrocarbon mixtures are so improved in ignition quality that they may be used as fuels.

This invention is predicated upon the discovery that compounds represented by the following general formula are effective in improving the ignition quality of a Diesel fuel when used therein in small amounts:

RI T-N=N-iJ-N0,

wherein T represents an aromatic group or nucleus, preferably phenyl or naphthyl, which may be unsubstituted or substituted with one or more of such groups as alkyl, aralkyl, aryl, alkaryl, halogen and nitro; R is a radical selected from the group consisting or alkyl, cycloalkyl, alkaryl, and aralkyl radicals and the same radicals containing a substituent such as halogen or nitro; and R," is a radical selected from the group consisting of R, halogen and nitro radicals. Typical of the compounds represented by the foregoing general Formula I are the following:

2- (phenylazo) -2-nitropropane, 2- (2-nitro-4-methyl phenylazo) -2-n itropropane, 2- (a-naphthylazo) -2-nitropropane,

1- (phenylazo) -l-chloro-1-nitropropane, 2-(2-chlorophenyla2o) -2-nitr0propane,

2- B-chlorophenylazo) -2-nitropropane, 2-(4-chlorophenylazo) -2-nitropropane, 2-(2,4,6-tribromophenylazo) 2 nitropropane,

and

i-(phenylazo)-1-phenyl-1,1-dinitromethane, etc.

Particularly preferred, however, of the compounds so represented are 2-(phenylazo)-2-nitropane, 2- (3-chlorophenylazo) 2 nitropropane and 2-(4-chlorophenylazo) -2'-nltropropane.

It will be apparent that all of the compounds represented above by the general Formula I con-' tain the following characterizing group:

wherein'the carbon atom, to which an azo group and a nitro groupare attached, is also attached to a radical or group such as those represented above, by R and R", thus being exclusive of attachment of hydrogen. Those related com,- pounds which contain more than one T-N=N- group attached to a carbon atom which is attached to a nitro group are also contemplated herein as effective Diesel fuel improving agents.

It has been found, however, that compounds containing the characterizing group:

' the following manner:

Illustrative of the compounds of this type (con- 4 and The Diesel fuel improving agents represented hereinabove by general Formula I and contem- .azonium salt, or the corresponding dianonium hydroxide. This preferred method of preparation is described in the following literature articles:

. Meyer and Ambuhl, Berichte 8, 751-2 (1875) and C. F. Feasley and Ed. W. Degering, J. Org. Chem.

8, 12 (1943); and is illustrated hereinafter by the preparation of several typical compounds represented by general Formula I. 4

As indicated above, one of the reactants used in the preferred procedure for the preparation 15 of the condensation products contemplated herein is a salt of a secondary nitroalkane. These salts are derivatives of secondary nitroalkanes which may be represented by the following general Formula V:

B'\H v B -N0, 4

whereinR' and R" are as defined hereinabove in connection with general Formula I.

It will be apparent that the salts of the fore- I going secondary nitroalkanes may be represented in the following manner:

n o I so I wherein R and R" are as previously defined and M is a metal, and is preferably an alkali metal,

such as sodium or potassium. These compounds are well known to those familiar with the art and it is believed that there is no need to refer to methods for their preparation otherthan those described in the foregoing literature references.

The diazonium compounds which are condensed with the aforesaid nitroalkanes may be represented by the following general formula;

(v11 T-Nr-X wherein '1 is as defined above, andX is a diazonium salt group such as one selected from the group consisting-oi -OH. -Cl, -N0a,

and ---OM wherein M is a metal such as sodium or potassium. I

From the foregoing, it will be apparent that a salt of a secondary nltroalkane (VI) may be directly'reacted with a 'diazonium compound of the type described above (VII) to form a compound oi the type represented above by general Formula I. It will also be apparent that a secresented above by general Formula I, are the typical compounds prepared'in the following examples:

EXAMPTE '1 lids-Numeric) -2-Nmoraoenur a-Naphtbyi amine. 1.9; parts by weight, was

added to asolution or 12.5 parts by w ight or water and 3.0 parts by weight of concentrated hydrochloric acid. The mixturewas diazotiaed at 0 to 5 C. with 1 part of sodium nitrite dissolved in 4.7 parts of water. To the dark colored solution thus formed was rapidly added 1.5 parts of cold 10% aqueous sodium hydroxide solution v and the sodium salt of zenitropropane. The lutmentioned compound was prepared by dissolving 1.2 parts of z-nitropropane in 5.4 parts of 10% aqueous sodium hydroxide. The yellow solid which first formed on the addition of sodium hydroxide solution and the sodium salt of 2-nitropropane changed over to a dark colored tarry like material. The organic layer which formed was separated from the aqueous layer, also.

formed. The organic product which contained nitrogen-was dissolved in Diesel fuel for a test of the cetane number of the resultant oil blend.

EXAMPLE 2 2- (d-Gntoaorumwmzo) -2-Nrrxol aorma To 3.1 parts by weight of para chloroanilinewas added a solution of 6.7 parts of concentrated hydrochloric acid in 11.2 parts of water. The mix.-

I ture was cooled to about 0 to 5 C. A sodium nitrite solution prepared by dissolving 1.7 parts of sodium nitrite in 3.1 parts of water and cooled to 0 to 5 C. was then slowly added to the para chlofotanilinte e hydrochloride in order to diazotize the The sodium salt of 2-nitropropane was prepared. by adding 2.2 parts of Z-nitropropane to an aqueous sodium hydroxide solution obtained by admixing one part of sodium hydroxide and 31.2 parts of water. The solution of 'the sodium salt was added to a sodium hydroxide solution prepared from 5.2 parts of sodium hydroxide and 62.5 parts of water. Ice, 62.5 parts, was then'added to the resulting solution. The diazomixture prepared above was then added to this ice solution. A yellow precipitate formed immediately. The yellow solid was separated from the mother liquid by filtration and recrystallized from hot ethyl alc'ohol. The product was a reddish-brown rystallinematerial melting at 64-67 c.; the literature discloses a melting point of 618 C. for 2-(4- chlorophenylazo) -2-nitropropane. The product was analyzed for chlorine and nitrogen, there- 0 sults'being as follows:

cm:- Found m Percent chlorine 14.: 15.6 lpercentmitmgen i8.2 18.5

EXAM 3 l-(PnnnYl-Azo) -1-Cm.oso-1-Nmoraorm Aniline (1.3 parts) was dissolved in an aqueou hydrochloric acid solution prepared from the 3 parts of concentrated hydrochloric acid and 13 parts of water. The resultingsolution'was cooled to'about 5 C. by the addition ofice. To the cold solution was added a coldsolution of sodium was then added 1.5 parts or cold 10 per cent aqueous sodium hydroxide'solution, which was foiiowed by an ice cold solution of thesodium salt of l-chloro-l-nitropropane prepared'trom 1.7

parts of l-chloro-l-nitropropane dissolved in 5.4

7opartsoi' a 10 percent aqueous sodium hydroxide solution. The temperature during these operations was maintained at to C. A yellow oil was formed which immediately changed to a dark reddish-brown oil which was separated from the mother liquid, washed with ice cold water and dried by contact with calcium chloride. This product contained nitrogen and chlorine.

The effectiveness of the compounds contemplated herein as Diesel fuel improving agents is illustrated by comparative tests of fuel oil blanks and..of fuel oil blends of said fuel 0115 containing typical compounds or condensation products. The fuel oils used in the test described hereinafterare representative .Jiesel fuels known in the art as catalytically cracked #2 fuel oils and are identified below in Table l as Fuel A and Fuel B.

Y The ignition quality of each of the fuels GA and B) and the fuel blends thereof was determined by acomparison of the same with a standard reference fuel in a converted C. F. R. engine using theignition delay method. The value shown in this test is expressed as the centane number" which is the percent by volume of cetane in amethyl naphthalene having the same combustion characteristics as the example under test (reference: Proc. Amer. Soc. Testing Materials, volume 38, I, 392 (1938)).

The results obtainedin the foregoing tests with fuel blends containing small amounts of the rep-' resentative compounds are tabulated in Tabl 2 below:

Table 2 Percent Increase Cetane Fuel Improving agent by in cetane weight number No.

A 2-(phenylazo)2-nitropropane l.0 37.8 4. A do 2.0 41.3 s. A 2- (anaphthylazo) 2 nitropropane 3.5 38.4 5. A 2-(2chlorophenylazo)-2- nitropropane l. 0 30. 4 3. A do 2.0 38.1 5. A l-phenylazo-l-chlorc-lnitropropane 2.0 36.6 2. B 2-(3chlorophenylazo)-2 nitropropane l. 0 38. 8 6. B do 2.0 41.9 9. B 2-(4chlorophenylazo)-2- nitropropane 1.0 37.8 5. B o 2.0 43.0 10. B 2-(2, 4, d-tribromophenylazo)2-nitropropane 0. 5 36. 6 4. B do 1.0 37.8 5.

It will be apparent from the foregoing test 'results that the compounds represented herelnabove' ingly, it is to be understood that the term Dleseli fuel" as used herein is inclusive of all types of non-viscous hydrocarbon oils suitable for use in any compression ignition engine.

We claim:

1. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therewith a minor proportion, suflicient to improve the ignition quality of the fuel, of a compound containing the characterizing group wherein T represents an aryl group, and the carbon atom as shown is attached to other than a hydrogen atom.

2. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therewith a minor proportion, from about 0.1 per cent to about 5.0 per cent, of acompound containing the characterizing group wherein T represents an aryl group, and the carbon atom as shown is attached to other than a hydrogen atom.

by general Formula I. are effective in improving a liquid hydrocarbon fuel in combustion ignition engines, said method being characterized by the 3. An improved'Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therewith a minor'proportion, sufficient to improve the ignition qualityof the fuel, of a compound represented by the general formula wherein T is selected from unsubstituted and substituted aryl groups; R is a radical selected from the group consisting of alkyl, cycloalkyl, aryl,

.alkaryl' and aralkyl radicals, and said radicals substituted with a substituent selected from the group consisting of halogen and nitro; and R." is

a radical selected from the group consisting of R, halogen and ultra radicals.

by the general formula RI 'r-N=N-o-N0 i wherein T is selected from unsubstituted and substituted aryl groups; R. is a radical selected from the group consisting of alkyl, cycloalkyl, aryl,

alkaryl and aralkyl radicals, and said radicals substituted with a substituent selected from the group consisting of halogen and nitro; and R" is a radical selected from the group consisting of R,

halogen andnitro radicals.

5. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therewith a. minor proportion, sumcient to improve the ignition quality of the fuel, of sented by the general formula a compound repre- T-N=N-( iN 02 N02 wherein T represents an aryl group; and R is a radical selected from the group consisting of alkyl,

cycloalkyl, aryl, alkaryl and aralkyl radicals, and

said radicals substituted with a substituent selected from the group consisting of halogen and nitro.

6. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therewith a minor proportion, sufiicient to improve the ignition quality of the fuel, of 2 -(4-chloro-ph'eny1azo)-2-nitropropane.

11. The method of accelerating the ignition quality of a liquid hydrocarbon fuel in an engine where the fuel is injected into the enginecylinder and ignites spontaneously therein. which comprises admixing with the fuel prior to its ignition in the cylinder, a minor proportion of a comignition quality of the fuel, of a compound represente. by the general formula wherein T is selected from unsubstituted and substituted aryl groups; and R is a radical se-' lected from the group consisting of alkyl, cycloalkyl, aryl, alkaryl and aralkyl radicals, and said radicals substituted witha substituent selected from the group consisting of halogen and nitro.

7. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therei with a minor proportion, suflicient to improve the ignition quality of the fuel,- of a compound represented by the general formula CH3 TN=,N-N O 2 v wherein T is selected from unsubstituted and substituted aryl groups. 8. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture therewith a minor proportion, suflicient to improve theignition quality of the fuel, of 2- (phenylazo) -2-nitropropane. I

9. An improved Diesel fuel comprising a nonviscous hydrocarbon oil and in admixture there-- with a minor proportion, sufllcient to improve the ignition quality of the fuel, of 2-(3-chloro-phenylazo) -2-nitropropane.

10. An improved Diesel fuel comprising a non-, viscous hydrocarbon oil and in admixture therewith a minor proportion, sufficient to improve the pound containing the characterizing group TN=N'-(:3N02

pound represented by the general formula I1! TN=NCN 01 I R wherein T is selected from unsubstituted and substituted aryl groups; R. is a radical selected from the group consisting of alkyd, cycloalkyl, aryl, alkaryl and a'ralkyl radicals, and said radicals substituted with a substituent selected from the group consisting of halogen and nitro; and R" is a radical selected from the group consisting of R, halogen and nitro radicals.

13. The method of accelerating the ignition quality of a liquid hydrocarbonfuel in an engine where the fuel is injected into the engine cylinder L and ignites spontaneously therein, which comprises admixing with the fuel prior to its ignition in the cylinder, a minor proportion ofa com pound represented by the general formula 1 v CH:

T-N=N--NO:

wherein T isselected from unsubstituted and substituted aryl groups.

EDWIN M. NTGAARD. JOHN MCCRACEN.

NATHAN H. HAMILTON. 

